Export the assembly from Solidworks in a compatible file format for blender (i.e. STL). In the options menu when you save from SW you can configure your STL (for example save all parts in one file for an assembly).
if i well remind (there's a long time i didn't it) Blender is a free-form modeling software and don't implement the constraint. You will only be able to import the shapes and their locations from Solidworks to Blender.
I do it , but i lose the constraint
save solidworks assembly files in .STL with all parts in the same file , import stl in blender.